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<div class="section" id="s-class-based-generic-views">
<span id="class-based-generic-views"></span><h1>Class-based generic views<a class="headerlink" href="#class-based-generic-views" title="Permalink to this headline">¶</a></h1>
<div class="versionadded">
<span class="title">New in Django 1.3:</span> <a class="reference internal" href="../releases/1.3.html"><em>Please see the release notes</em></a></div>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p>Prior to Django 1.3, generic views were implemented as functions. The
function-based implementation has been deprecated in favor of the
class-based approach described here.</p>
<p class="last">For details on the previous generic views implementation,
see the <a class="reference internal" href="generic-views.html"><em>topic guide</em></a> and
<a class="reference internal" href="../ref/generic-views.html"><em>detailed reference</em></a>.</p>
</div>
<p>Writing Web applications can be monotonous, because we repeat certain patterns
again and again. Django tries to take away some of that monotony at the model
and template layers, but Web developers also experience this boredom at the view
level.</p>
<p>Django’s <em>generic views</em> were developed to ease that pain. They take certain
common idioms and patterns found in view development and abstract them so that
you can quickly write common views of data without having to write too much
code.</p>
<p>We can recognize certain common tasks, like displaying a list of objects, and
write code that displays a list of <em>any</em> object. Then the model in question can
be passed as an extra argument to the URLconf.</p>
<p>Django ships with generic views to do the following:</p>
<ul class="simple">
<li>Perform common “simple” tasks: redirect to a different page and
render a given template.</li>
<li>Display list and detail pages for a single object. If we were creating an
application to manage conferences then a <tt class="docutils literal"><span class="pre">TalkListView</span></tt> and a
<tt class="docutils literal"><span class="pre">RegisteredUserListView</span></tt> would be examples of list views. A single
talk page is an example of what we call a “detail” view.</li>
<li>Present date-based objects in year/month/day archive pages,
associated detail, and “latest” pages.
<a class="reference external" href="https://www.djangoproject.com/weblog/">The Django Weblog</a>‘s
year, month, and day archives are built with these, as would be a typical
newspaper’s archives.</li>
<li>Allow users to create, update, and delete objects – with or
without authorization.</li>
</ul>
<p>Taken together, these views provide easy interfaces to perform the most common
tasks developers encounter.</p>
<div class="section" id="s-simple-usage">
<span id="simple-usage"></span><h2>Simple usage<a class="headerlink" href="#simple-usage" title="Permalink to this headline">¶</a></h2>
<p>Class-based generic views (and any class-based views that inherit from
the base classes Django provides) can be configured in two
ways: subclassing, or passing in arguments directly in the URLconf.</p>
<p>When you subclass a class-based view, you can override attributes
(such as the <tt class="docutils literal"><span class="pre">template_name</span></tt>) or methods (such as <tt class="docutils literal"><span class="pre">get_context_data</span></tt>)
in your subclass to provide new values or methods. Consider, for example,
a view that just displays one template, <tt class="docutils literal"><span class="pre">about.html</span></tt>. Django has a
generic view to do this - <a class="reference internal" href="../ref/class-based-views.html#django.views.generic.base.TemplateView" title="django.views.generic.base.TemplateView"><tt class="xref py py-class docutils literal"><span class="pre">TemplateView</span></tt></a> -
so we can just subclass it, and override the template name:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="c"># some_app/views.py</span>
<span class="kn">from</span> <span class="nn">django.views.generic</span> <span class="kn">import</span> <span class="n">TemplateView</span>
<span class="k">class</span> <span class="nc">AboutView</span><span class="p">(</span><span class="n">TemplateView</span><span class="p">):</span>
<span class="n">template_name</span> <span class="o">=</span> <span class="s">"about.html"</span>
</pre></div>
</div>
<p>Then, we just need to add this new view into our URLconf. As the class-based
views themselves are classes, we point the URL to the <tt class="docutils literal"><span class="pre">as_view</span></tt> class method
instead, which is the entry point for class-based views:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="c"># urls.py</span>
<span class="kn">from</span> <span class="nn">django.conf.urls</span> <span class="kn">import</span> <span class="n">patterns</span><span class="p">,</span> <span class="n">url</span><span class="p">,</span> <span class="n">include</span>
<span class="kn">from</span> <span class="nn">some_app.views</span> <span class="kn">import</span> <span class="n">AboutView</span>
<span class="n">urlpatterns</span> <span class="o">=</span> <span class="n">patterns</span><span class="p">(</span><span class="s">''</span><span class="p">,</span>
<span class="p">(</span><span class="s">r'^about/'</span><span class="p">,</span> <span class="n">AboutView</span><span class="o">.</span><span class="n">as_view</span><span class="p">()),</span>
<span class="p">)</span>
</pre></div>
</div>
<p>Alternatively, if you’re only changing a few simple attributes on a
class-based view, you can simply pass the new attributes into the <tt class="docutils literal"><span class="pre">as_view</span></tt>
method call itself:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">django.conf.urls</span> <span class="kn">import</span> <span class="n">patterns</span><span class="p">,</span> <span class="n">url</span><span class="p">,</span> <span class="n">include</span>
<span class="kn">from</span> <span class="nn">django.views.generic</span> <span class="kn">import</span> <span class="n">TemplateView</span>
<span class="n">urlpatterns</span> <span class="o">=</span> <span class="n">patterns</span><span class="p">(</span><span class="s">''</span><span class="p">,</span>
<span class="p">(</span><span class="s">r'^about/'</span><span class="p">,</span> <span class="n">TemplateView</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span><span class="n">template_name</span><span class="o">=</span><span class="s">"about.html"</span><span class="p">)),</span>
<span class="p">)</span>
</pre></div>
</div>
<p>A similar overriding pattern can be used for the <tt class="docutils literal"><span class="pre">url</span></tt> attribute on
<a class="reference internal" href="../ref/class-based-views.html#django.views.generic.base.RedirectView" title="django.views.generic.base.RedirectView"><tt class="xref py py-class docutils literal"><span class="pre">RedirectView</span></tt></a>, another simple
generic view.</p>
</div>
<div class="section" id="s-generic-views-of-objects">
<span id="generic-views-of-objects"></span><h2>Generic views of objects<a class="headerlink" href="#generic-views-of-objects" title="Permalink to this headline">¶</a></h2>
<p><a class="reference internal" href="../ref/class-based-views.html#django.views.generic.base.TemplateView" title="django.views.generic.base.TemplateView"><tt class="xref py py-class docutils literal"><span class="pre">TemplateView</span></tt></a> certainly is useful,
but Django’s generic views really shine when it comes to presenting
views of your database content. Because it’s such a common task,
Django comes with a handful of built-in generic views that make
generating list and detail views of objects incredibly easy.</p>
<p>Let’s take a look at one of these generic views: the “object list” view. We’ll
be using these models:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="c"># models.py</span>
<span class="kn">from</span> <span class="nn">django.db</span> <span class="kn">import</span> <span class="n">models</span>
<span class="k">class</span> <span class="nc">Publisher</span><span class="p">(</span><span class="n">models</span><span class="o">.</span><span class="n">Model</span><span class="p">):</span>
<span class="n">name</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">CharField</span><span class="p">(</span><span class="n">max_length</span><span class="o">=</span><span class="mi">30</span><span class="p">)</span>
<span class="n">address</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">CharField</span><span class="p">(</span><span class="n">max_length</span><span class="o">=</span><span class="mi">50</span><span class="p">)</span>
<span class="n">city</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">CharField</span><span class="p">(</span><span class="n">max_length</span><span class="o">=</span><span class="mi">60</span><span class="p">)</span>
<span class="n">state_province</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">CharField</span><span class="p">(</span><span class="n">max_length</span><span class="o">=</span><span class="mi">30</span><span class="p">)</span>
<span class="n">country</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">CharField</span><span class="p">(</span><span class="n">max_length</span><span class="o">=</span><span class="mi">50</span><span class="p">)</span>
<span class="n">website</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">URLField</span><span class="p">()</span>
<span class="k">class</span> <span class="nc">Meta</span><span class="p">:</span>
<span class="n">ordering</span> <span class="o">=</span> <span class="p">[</span><span class="s">"-name"</span><span class="p">]</span>
<span class="k">def</span> <span class="nf">__unicode__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">name</span>
<span class="k">class</span> <span class="nc">Book</span><span class="p">(</span><span class="n">models</span><span class="o">.</span><span class="n">Model</span><span class="p">):</span>
<span class="n">title</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">CharField</span><span class="p">(</span><span class="n">max_length</span><span class="o">=</span><span class="mi">100</span><span class="p">)</span>
<span class="n">authors</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">ManyToManyField</span><span class="p">(</span><span class="s">'Author'</span><span class="p">)</span>
<span class="n">publisher</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">ForeignKey</span><span class="p">(</span><span class="n">Publisher</span><span class="p">)</span>
<span class="n">publication_date</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">DateField</span><span class="p">()</span>
</pre></div>
</div>
<p>To build a list page of all publishers, we’d use a URLconf along these lines:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">django.conf.urls</span> <span class="kn">import</span> <span class="n">patterns</span><span class="p">,</span> <span class="n">url</span><span class="p">,</span> <span class="n">include</span>
<span class="kn">from</span> <span class="nn">django.views.generic</span> <span class="kn">import</span> <span class="n">ListView</span>
<span class="kn">from</span> <span class="nn">books.models</span> <span class="kn">import</span> <span class="n">Publisher</span>
<span class="n">urlpatterns</span> <span class="o">=</span> <span class="n">patterns</span><span class="p">(</span><span class="s">''</span><span class="p">,</span>
<span class="p">(</span><span class="s">r'^publishers/$'</span><span class="p">,</span> <span class="n">ListView</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span>
<span class="n">model</span><span class="o">=</span><span class="n">Publisher</span><span class="p">,</span>
<span class="p">)),</span>
<span class="p">)</span>
</pre></div>
</div>
<p>That’s all the Python code we need to write. We still need to write a template,
however. We could explicitly tell the view which template to use
by including a <tt class="docutils literal"><span class="pre">template_name</span></tt> key in the arguments to as_view, but in
the absence of an explicit template Django will infer one from the object’s
name. In this case, the inferred template will be
<tt class="docutils literal"><span class="pre">"books/publisher_list.html"</span></tt> – the “books” part comes from the name of the
app that defines the model, while the “publisher” bit is just the lowercased
version of the model’s name.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p>Thus, when (for example) the <tt class="xref py py-class docutils literal"><span class="pre">django.template.loaders.app_directories.Loader</span></tt>
template loader is enabled in <a class="reference internal" href="../ref/settings.html#std:setting-TEMPLATE_LOADERS"><tt class="xref std std-setting docutils literal"><span class="pre">TEMPLATE_LOADERS</span></tt></a>, the template
location would be:</p>
<div class="last highlight-python"><pre>/path/to/project/books/templates/books/publisher_list.html</pre>
</div>
</div>
<p>This template will be rendered against a context containing a variable called
<tt class="docutils literal"><span class="pre">object_list</span></tt> that contains all the publisher objects. A very simple template
might look like the following:</p>
<div class="highlight-html+django"><div class="highlight"><pre><span class="cp">{%</span> <span class="k">extends</span> <span class="s2">"base.html"</span> <span class="cp">%}</span>
<span class="cp">{%</span> <span class="k">block</span> <span class="nv">content</span> <span class="cp">%}</span>
<span class="nt"><h2></span>Publishers<span class="nt"></h2></span>
<span class="nt"><ul></span>
<span class="cp">{%</span> <span class="k">for</span> <span class="nv">publisher</span> <span class="k">in</span> <span class="nv">object_list</span> <span class="cp">%}</span>
<span class="nt"><li></span><span class="cp">{{</span> <span class="nv">publisher.name</span> <span class="cp">}}</span><span class="nt"></li></span>
<span class="cp">{%</span> <span class="k">endfor</span> <span class="cp">%}</span>
<span class="nt"></ul></span>
<span class="cp">{%</span> <span class="k">endblock</span> <span class="cp">%}</span>
</pre></div>
</div>
<p>That’s really all there is to it. All the cool features of generic views come
from changing the “info” dictionary passed to the generic view. The
<a class="reference internal" href="../ref/class-based-views.html"><em>generic views reference</em></a> documents all the generic
views and their options in detail; the rest of this document will consider
some of the common ways you might customize and extend generic views.</p>
</div>
<div class="section" id="s-extending-generic-views">
<span id="extending-generic-views"></span><h2>Extending generic views<a class="headerlink" href="#extending-generic-views" title="Permalink to this headline">¶</a></h2>
<p>There’s no question that using generic views can speed up development
substantially. In most projects, however, there comes a moment when the
generic views no longer suffice. Indeed, the most common question asked by new
Django developers is how to make generic views handle a wider array of
situations.</p>
<p>This is one of the reasons generic views were redesigned for the 1.3 release -
previously, they were just view functions with a bewildering array of options;
now, rather than passing in a large amount of configuration in the URLconf,
the recommended way to extend generic views is to subclass them, and override
their attributes or methods.</p>
<div class="section" id="s-making-friendly-template-contexts">
<span id="making-friendly-template-contexts"></span><h3>Making “friendly” template contexts<a class="headerlink" href="#making-friendly-template-contexts" title="Permalink to this headline">¶</a></h3>
<p>You might have noticed that our sample publisher list template stores
all the publishers in a variable named <tt class="docutils literal"><span class="pre">object_list</span></tt>. While this
works just fine, it isn’t all that “friendly” to template authors:
they have to “just know” that they’re dealing with publishers here.</p>
<p>Well, if you’re dealing with a model object, this is already done for
you. When you are dealing with an object or queryset, Django is able
to populate the context using the verbose name (or the plural verbose
name, in the case of a list of objects) of the object being displayed.
This is provided in addition to the default <tt class="docutils literal"><span class="pre">object_list</span></tt> entry, but
contains exactly the same data.</p>
<p>If the verbose name (or plural verbose name) still isn’t a good match,
you can manually set the name of the context variable. The
<tt class="docutils literal"><span class="pre">context_object_name</span></tt> attribute on a generic view specifies the
context variable to use. In this example, we’ll override it in the
URLconf, since it’s a simple change:</p>
<pre class="literal-block">
urlpatterns = patterns('',
(r'^publishers/$', ListView.as_view(
model=Publisher,
<strong>context_object_name="publisher_list",</strong>
)),
)
</pre>
<p>Providing a useful <tt class="docutils literal"><span class="pre">context_object_name</span></tt> is always a good idea. Your
coworkers who design templates will thank you.</p>
</div>
<div class="section" id="s-adding-extra-context">
<span id="adding-extra-context"></span><h3>Adding extra context<a class="headerlink" href="#adding-extra-context" title="Permalink to this headline">¶</a></h3>
<p>Often you simply need to present some extra information beyond that
provided by the generic view. For example, think of showing a list of
all the books on each publisher detail page. The
<a class="reference internal" href="../ref/class-based-views.html#django.views.generic.detail.DetailView" title="django.views.generic.detail.DetailView"><tt class="xref py py-class docutils literal"><span class="pre">DetailView</span></tt></a> generic view provides
the publisher to the context, but it seems there’s no way to get
additional information in that template.</p>
<p>However, there is; you can subclass
<a class="reference internal" href="../ref/class-based-views.html#django.views.generic.detail.DetailView" title="django.views.generic.detail.DetailView"><tt class="xref py py-class docutils literal"><span class="pre">DetailView</span></tt></a> and provide your own
implementation of the <tt class="docutils literal"><span class="pre">get_context_data</span></tt> method. The default
implementation of this that comes with
<a class="reference internal" href="../ref/class-based-views.html#django.views.generic.detail.DetailView" title="django.views.generic.detail.DetailView"><tt class="xref py py-class docutils literal"><span class="pre">DetailView</span></tt></a> simply adds in the
object being displayed to the template, but you can override it to show
more:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">django.views.generic</span> <span class="kn">import</span> <span class="n">DetailView</span>
<span class="kn">from</span> <span class="nn">books.models</span> <span class="kn">import</span> <span class="n">Publisher</span><span class="p">,</span> <span class="n">Book</span>
<span class="k">class</span> <span class="nc">PublisherDetailView</span><span class="p">(</span><span class="n">DetailView</span><span class="p">):</span>
<span class="n">context_object_name</span> <span class="o">=</span> <span class="s">"publisher"</span>
<span class="n">model</span> <span class="o">=</span> <span class="n">Publisher</span>
<span class="k">def</span> <span class="nf">get_context_data</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="c"># Call the base implementation first to get a context</span>
<span class="n">context</span> <span class="o">=</span> <span class="nb">super</span><span class="p">(</span><span class="n">PublisherDetailView</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">get_context_data</span><span class="p">(</span><span class="o">**</span><span class="n">kwargs</span><span class="p">)</span>
<span class="c"># Add in a QuerySet of all the books</span>
<span class="n">context</span><span class="p">[</span><span class="s">'book_list'</span><span class="p">]</span> <span class="o">=</span> <span class="n">Book</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">all</span><span class="p">()</span>
<span class="k">return</span> <span class="n">context</span>
</pre></div>
</div>
</div>
<div class="section" id="s-viewing-subsets-of-objects">
<span id="viewing-subsets-of-objects"></span><h3>Viewing subsets of objects<a class="headerlink" href="#viewing-subsets-of-objects" title="Permalink to this headline">¶</a></h3>
<p>Now let’s take a closer look at the <tt class="docutils literal"><span class="pre">model</span></tt> argument we’ve been
using all along. The <tt class="docutils literal"><span class="pre">model</span></tt> argument, which specifies the database
model that the view will operate upon, is available on all the
generic views that operate on a single object or a collection of
objects. However, the <tt class="docutils literal"><span class="pre">model</span></tt> argument is not the only way to
specify the objects that the view will operate upon – you can also
specify the list of objects using the <tt class="docutils literal"><span class="pre">queryset</span></tt> argument:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">django.views.generic</span> <span class="kn">import</span> <span class="n">DetailView</span>
<span class="kn">from</span> <span class="nn">books.models</span> <span class="kn">import</span> <span class="n">Publisher</span><span class="p">,</span> <span class="n">Book</span>
<span class="k">class</span> <span class="nc">PublisherDetailView</span><span class="p">(</span><span class="n">DetailView</span><span class="p">):</span>
<span class="n">context_object_name</span> <span class="o">=</span> <span class="s">"publisher"</span>
<span class="n">queryset</span> <span class="o">=</span> <span class="n">Publisher</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">all</span><span class="p">()</span>
</pre></div>
</div>
<p>Specifying <tt class="docutils literal"><span class="pre">model</span> <span class="pre">=</span> <span class="pre">Publisher</span></tt> is really just shorthand for saying
<tt class="docutils literal"><span class="pre">queryset</span> <span class="pre">=</span> <span class="pre">Publisher.objects.all()</span></tt>. However, by using <tt class="docutils literal"><span class="pre">queryset</span></tt>
to define a filtered list of objects you can be more specific about the
objects that will be visible in the view (see <a class="reference internal" href="db/queries.html"><em>Making queries</em></a>
for more information about <tt class="xref py py-class docutils literal"><span class="pre">QuerySet</span></tt> objects, and see the
<a class="reference internal" href="../ref/class-based-views.html"><em>class-based views reference</em></a> for the complete
details).</p>
<p>To pick a simple example, we might want to order a list of books by
publication date, with the most recent first:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">urlpatterns</span> <span class="o">=</span> <span class="n">patterns</span><span class="p">(</span><span class="s">''</span><span class="p">,</span>
<span class="p">(</span><span class="s">r'^publishers/$'</span><span class="p">,</span> <span class="n">ListView</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span>
<span class="n">queryset</span><span class="o">=</span><span class="n">Publisher</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">all</span><span class="p">(),</span>
<span class="n">context_object_name</span><span class="o">=</span><span class="s">"publisher_list"</span><span class="p">,</span>
<span class="p">)),</span>
<span class="p">(</span><span class="s">r'^books/$'</span><span class="p">,</span> <span class="n">ListView</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span>
<span class="n">queryset</span><span class="o">=</span><span class="n">Book</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">order_by</span><span class="p">(</span><span class="s">"-publication_date"</span><span class="p">),</span>
<span class="n">context_object_name</span><span class="o">=</span><span class="s">"book_list"</span><span class="p">,</span>
<span class="p">)),</span>
<span class="p">)</span>
</pre></div>
</div>
<p>That’s a pretty simple example, but it illustrates the idea nicely. Of course,
you’ll usually want to do more than just reorder objects. If you want to
present a list of books by a particular publisher, you can use the same
technique (here, illustrated using subclassing rather than by passing arguments
in the URLconf):</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">django.views.generic</span> <span class="kn">import</span> <span class="n">ListView</span>
<span class="kn">from</span> <span class="nn">books.models</span> <span class="kn">import</span> <span class="n">Book</span>
<span class="k">class</span> <span class="nc">AcmeBookListView</span><span class="p">(</span><span class="n">ListView</span><span class="p">):</span>
<span class="n">context_object_name</span> <span class="o">=</span> <span class="s">"book_list"</span>
<span class="n">queryset</span> <span class="o">=</span> <span class="n">Book</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">publisher__name</span><span class="o">=</span><span class="s">"Acme Publishing"</span><span class="p">)</span>
<span class="n">template_name</span> <span class="o">=</span> <span class="s">"books/acme_list.html"</span>
</pre></div>
</div>
<p>Notice that along with a filtered <tt class="docutils literal"><span class="pre">queryset</span></tt>, we’re also using a custom
template name. If we didn’t, the generic view would use the same template as the
“vanilla” object list, which might not be what we want.</p>
<p>Also notice that this isn’t a very elegant way of doing publisher-specific
books. If we want to add another publisher page, we’d need another handful of
lines in the URLconf, and more than a few publishers would get unreasonable.
We’ll deal with this problem in the next section.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">If you get a 404 when requesting <tt class="docutils literal"><span class="pre">/books/acme/</span></tt>, check to ensure you
actually have a Publisher with the name ‘ACME Publishing’. Generic
views have an <tt class="docutils literal"><span class="pre">allow_empty</span></tt> parameter for this case. See the
<a class="reference internal" href="../ref/class-based-views.html"><em>class-based-views reference</em></a> for more details.</p>
</div>
</div>
<div class="section" id="s-dynamic-filtering">
<span id="dynamic-filtering"></span><h3>Dynamic filtering<a class="headerlink" href="#dynamic-filtering" title="Permalink to this headline">¶</a></h3>
<p>Another common need is to filter down the objects given in a list page by some
key in the URL. Earlier we hard-coded the publisher’s name in the URLconf, but
what if we wanted to write a view that displayed all the books by some arbitrary
publisher?</p>
<p>Handily, the <tt class="docutils literal"><span class="pre">ListView</span></tt> has a
<tt class="xref py py-meth docutils literal"><span class="pre">get_queryset()</span></tt> method we can
override. Previously, it has just been returning the value of the <tt class="docutils literal"><span class="pre">queryset</span></tt>
attribute, but now we can add more logic.</p>
<p>The key part to making this work is that when class-based views are called,
various useful things are stored on <tt class="docutils literal"><span class="pre">self</span></tt>; as well as the request
(<tt class="docutils literal"><span class="pre">self.request</span></tt>) this includes the positional (<tt class="docutils literal"><span class="pre">self.args</span></tt>) and name-based
(<tt class="docutils literal"><span class="pre">self.kwargs</span></tt>) arguments captured according to the URLconf.</p>
<p>Here, we have a URLconf with a single captured group:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">books.views</span> <span class="kn">import</span> <span class="n">PublisherBookListView</span>
<span class="n">urlpatterns</span> <span class="o">=</span> <span class="n">patterns</span><span class="p">(</span><span class="s">''</span><span class="p">,</span>
<span class="p">(</span><span class="s">r'^books/(\w+)/$'</span><span class="p">,</span> <span class="n">PublisherBookListView</span><span class="o">.</span><span class="n">as_view</span><span class="p">()),</span>
<span class="p">)</span>
</pre></div>
</div>
<p>Next, we’ll write the <tt class="docutils literal"><span class="pre">PublisherBookListView</span></tt> view itself:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">django.shortcuts</span> <span class="kn">import</span> <span class="n">get_object_or_404</span>
<span class="kn">from</span> <span class="nn">django.views.generic</span> <span class="kn">import</span> <span class="n">ListView</span>
<span class="kn">from</span> <span class="nn">books.models</span> <span class="kn">import</span> <span class="n">Book</span><span class="p">,</span> <span class="n">Publisher</span>
<span class="k">class</span> <span class="nc">PublisherBookListView</span><span class="p">(</span><span class="n">ListView</span><span class="p">):</span>
<span class="n">context_object_name</span> <span class="o">=</span> <span class="s">"book_list"</span>
<span class="n">template_name</span> <span class="o">=</span> <span class="s">"books/books_by_publisher.html"</span>
<span class="k">def</span> <span class="nf">get_queryset</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">publisher</span> <span class="o">=</span> <span class="n">get_object_or_404</span><span class="p">(</span><span class="n">Publisher</span><span class="p">,</span> <span class="n">name__iexact</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">args</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span>
<span class="k">return</span> <span class="n">Book</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">publisher</span><span class="o">=</span><span class="n">publisher</span><span class="p">)</span>
</pre></div>
</div>
<p>As you can see, it’s quite easy to add more logic to the queryset selection;
if we wanted, we could use <tt class="docutils literal"><span class="pre">self.request.user</span></tt> to filter using the current
user, or other more complex logic.</p>
<p>We can also add the publisher into the context at the same time, so we can
use it in the template:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">class</span> <span class="nc">PublisherBookListView</span><span class="p">(</span><span class="n">ListView</span><span class="p">):</span>
<span class="n">context_object_name</span> <span class="o">=</span> <span class="s">"book_list"</span>
<span class="n">template_name</span> <span class="o">=</span> <span class="s">"books/books_by_publisher.html"</span>
<span class="k">def</span> <span class="nf">get_queryset</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">publisher</span> <span class="o">=</span> <span class="n">get_object_or_404</span><span class="p">(</span><span class="n">Publisher</span><span class="p">,</span> <span class="n">name__iexact</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">args</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span>
<span class="k">return</span> <span class="n">Book</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">publisher</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">publisher</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">get_context_data</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="c"># Call the base implementation first to get a context</span>
<span class="n">context</span> <span class="o">=</span> <span class="nb">super</span><span class="p">(</span><span class="n">PublisherBookListView</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">get_context_data</span><span class="p">(</span><span class="o">**</span><span class="n">kwargs</span><span class="p">)</span>
<span class="c"># Add in the publisher</span>
<span class="n">context</span><span class="p">[</span><span class="s">'publisher'</span><span class="p">]</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">publisher</span>
<span class="k">return</span> <span class="n">context</span>
</pre></div>
</div>
</div>
<div class="section" id="s-performing-extra-work">
<span id="performing-extra-work"></span><h3>Performing extra work<a class="headerlink" href="#performing-extra-work" title="Permalink to this headline">¶</a></h3>
<p>The last common pattern we’ll look at involves doing some extra work before
or after calling the generic view.</p>
<p>Imagine we had a <tt class="docutils literal"><span class="pre">last_accessed</span></tt> field on our <tt class="docutils literal"><span class="pre">Author</span></tt> object that we were
using to keep track of the last time anybody looked at that author:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="c"># models.py</span>
<span class="k">class</span> <span class="nc">Author</span><span class="p">(</span><span class="n">models</span><span class="o">.</span><span class="n">Model</span><span class="p">):</span>
<span class="n">salutation</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">CharField</span><span class="p">(</span><span class="n">max_length</span><span class="o">=</span><span class="mi">10</span><span class="p">)</span>
<span class="n">first_name</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">CharField</span><span class="p">(</span><span class="n">max_length</span><span class="o">=</span><span class="mi">30</span><span class="p">)</span>
<span class="n">last_name</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">CharField</span><span class="p">(</span><span class="n">max_length</span><span class="o">=</span><span class="mi">40</span><span class="p">)</span>
<span class="n">email</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">EmailField</span><span class="p">()</span>
<span class="n">headshot</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">ImageField</span><span class="p">(</span><span class="n">upload_to</span><span class="o">=</span><span class="s">'/tmp'</span><span class="p">)</span>
<span class="n">last_accessed</span> <span class="o">=</span> <span class="n">models</span><span class="o">.</span><span class="n">DateTimeField</span><span class="p">()</span>
</pre></div>
</div>
<p>The generic <tt class="docutils literal"><span class="pre">DetailView</span></tt> class, of course, wouldn’t know anything about this
field, but once again we could easily write a custom view to keep that field
updated.</p>
<p>First, we’d need to add an author detail bit in the URLconf to point to a
custom view:</p>
<pre class="literal-block">
from books.views import AuthorDetailView
urlpatterns = patterns('',
#...
<strong>(r'^authors/(?P<pk>\d+)/$', AuthorDetailView.as_view()),</strong>
)
</pre>
<p>Then we’d write our new view – <tt class="docutils literal"><span class="pre">get_object</span></tt> is the method that retrieves the
object – so we simply override it and wrap the call:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">datetime</span>
<span class="kn">from</span> <span class="nn">books.models</span> <span class="kn">import</span> <span class="n">Author</span>
<span class="kn">from</span> <span class="nn">django.views.generic</span> <span class="kn">import</span> <span class="n">DetailView</span>
<span class="kn">from</span> <span class="nn">django.shortcuts</span> <span class="kn">import</span> <span class="n">get_object_or_404</span>
<span class="k">class</span> <span class="nc">AuthorDetailView</span><span class="p">(</span><span class="n">DetailView</span><span class="p">):</span>
<span class="n">queryset</span> <span class="o">=</span> <span class="n">Author</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">all</span><span class="p">()</span>
<span class="k">def</span> <span class="nf">get_object</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="c"># Call the superclass</span>
<span class="nb">object</span> <span class="o">=</span> <span class="nb">super</span><span class="p">(</span><span class="n">AuthorDetailView</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">get_object</span><span class="p">()</span>
<span class="c"># Record the last accessed date</span>
<span class="nb">object</span><span class="o">.</span><span class="n">last_accessed</span> <span class="o">=</span> <span class="n">datetime</span><span class="o">.</span><span class="n">datetime</span><span class="o">.</span><span class="n">now</span><span class="p">()</span>
<span class="nb">object</span><span class="o">.</span><span class="n">save</span><span class="p">()</span>
<span class="c"># Return the object</span>
<span class="k">return</span> <span class="nb">object</span>
</pre></div>
</div>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">This code won’t actually work unless you create a
<tt class="docutils literal"><span class="pre">books/author_detail.html</span></tt> template.</p>
</div>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p>The URLconf here uses the named group <tt class="docutils literal"><span class="pre">pk</span></tt> - this name is the default
name that <tt class="docutils literal"><span class="pre">DetailView</span></tt> uses to find the value of the primary key used to
filter the queryset.</p>
<p class="last">If you want to change it, you’ll need to do your own <tt class="docutils literal"><span class="pre">get()</span></tt> call
on <tt class="docutils literal"><span class="pre">self.queryset</span></tt> using the new named parameter from <tt class="docutils literal"><span class="pre">self.kwargs</span></tt>.</p>
</div>
</div>
<div class="section" id="s-more-than-just-html">
<span id="more-than-just-html"></span><h3>More than just HTML<a class="headerlink" href="#more-than-just-html" title="Permalink to this headline">¶</a></h3>
<p>So far, we’ve been focusing on rendering templates to generate
responses. However, that’s not all generic views can do.</p>
<p>Each generic view is composed out of a series of mixins, and each
mixin contributes a little piece of the entire view. Some of these
mixins – such as
<a class="reference internal" href="../ref/class-based-views.html#django.views.generic.base.TemplateResponseMixin" title="django.views.generic.base.TemplateResponseMixin"><tt class="xref py py-class docutils literal"><span class="pre">TemplateResponseMixin</span></tt></a> – are
specifically designed for rendering content to an HTML response using a
template. However, you can write your own mixins that perform
different rendering behavior.</p>
<p>For example, a simple JSON mixin might look something like this:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">django</span> <span class="kn">import</span> <span class="n">http</span>
<span class="kn">from</span> <span class="nn">django.utils</span> <span class="kn">import</span> <span class="n">simplejson</span> <span class="k">as</span> <span class="n">json</span>
<span class="k">class</span> <span class="nc">JSONResponseMixin</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">render_to_response</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">context</span><span class="p">):</span>
<span class="s">"Returns a JSON response containing 'context' as payload"</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">get_json_response</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">convert_context_to_json</span><span class="p">(</span><span class="n">context</span><span class="p">))</span>
<span class="k">def</span> <span class="nf">get_json_response</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">content</span><span class="p">,</span> <span class="o">**</span><span class="n">httpresponse_kwargs</span><span class="p">):</span>
<span class="s">"Construct an `HttpResponse` object."</span>
<span class="k">return</span> <span class="n">http</span><span class="o">.</span><span class="n">HttpResponse</span><span class="p">(</span><span class="n">content</span><span class="p">,</span>
<span class="n">content_type</span><span class="o">=</span><span class="s">'application/json'</span><span class="p">,</span>
<span class="o">**</span><span class="n">httpresponse_kwargs</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">convert_context_to_json</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">context</span><span class="p">):</span>
<span class="s">"Convert the context dictionary into a JSON object"</span>
<span class="c"># Note: This is *EXTREMELY* naive; in reality, you'll need</span>
<span class="c"># to do much more complex handling to ensure that arbitrary</span>
<span class="c"># objects -- such as Django model instances or querysets</span>
<span class="c"># -- can be serialized as JSON.</span>
<span class="k">return</span> <span class="n">json</span><span class="o">.</span><span class="n">dumps</span><span class="p">(</span><span class="n">context</span><span class="p">)</span>
</pre></div>
</div>
<p>Then, you could build a JSON-returning
<a class="reference internal" href="../ref/class-based-views.html#django.views.generic.detail.DetailView" title="django.views.generic.detail.DetailView"><tt class="xref py py-class docutils literal"><span class="pre">DetailView</span></tt></a> by mixing your
<tt class="xref py py-class docutils literal"><span class="pre">JSONResponseMixin</span></tt> with the
<a class="reference internal" href="../ref/class-based-views.html#django.views.generic.detail.BaseDetailView" title="django.views.generic.detail.BaseDetailView"><tt class="xref py py-class docutils literal"><span class="pre">BaseDetailView</span></tt></a> – (the
<a class="reference internal" href="../ref/class-based-views.html#django.views.generic.detail.DetailView" title="django.views.generic.detail.DetailView"><tt class="xref py py-class docutils literal"><span class="pre">DetailView</span></tt></a> before template
rendering behavior has been mixed in):</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">class</span> <span class="nc">JSONDetailView</span><span class="p">(</span><span class="n">JSONResponseMixin</span><span class="p">,</span> <span class="n">BaseDetailView</span><span class="p">):</span>
<span class="k">pass</span>
</pre></div>
</div>
<p>This view can then be deployed in the same way as any other
<a class="reference internal" href="../ref/class-based-views.html#django.views.generic.detail.DetailView" title="django.views.generic.detail.DetailView"><tt class="xref py py-class docutils literal"><span class="pre">DetailView</span></tt></a>, with exactly the
same behavior – except for the format of the response.</p>
<p>If you want to be really adventurous, you could even mix a
<a class="reference internal" href="../ref/class-based-views.html#django.views.generic.detail.DetailView" title="django.views.generic.detail.DetailView"><tt class="xref py py-class docutils literal"><span class="pre">DetailView</span></tt></a> subclass that is able
to return <em>both</em> HTML and JSON content, depending on some property of
the HTTP request, such as a query argument or a HTTP header. Just mix
in both the <tt class="xref py py-class docutils literal"><span class="pre">JSONResponseMixin</span></tt> and a
<a class="reference internal" href="../ref/class-based-views.html#django.views.generic.detail.SingleObjectTemplateResponseMixin" title="django.views.generic.detail.SingleObjectTemplateResponseMixin"><tt class="xref py py-class docutils literal"><span class="pre">SingleObjectTemplateResponseMixin</span></tt></a>,
and override the implementation of <tt class="xref py py-func docutils literal"><span class="pre">render_to_response()</span></tt> to defer
to the appropriate subclass depending on the type of response that the user
requested:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="k">class</span> <span class="nc">HybridDetailView</span><span class="p">(</span><span class="n">JSONResponseMixin</span><span class="p">,</span> <span class="n">SingleObjectTemplateResponseMixin</span><span class="p">,</span> <span class="n">BaseDetailView</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">render_to_response</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">context</span><span class="p">):</span>
<span class="c"># Look for a 'format=json' GET argument</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">request</span><span class="o">.</span><span class="n">GET</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="s">'format'</span><span class="p">,</span><span class="s">'html'</span><span class="p">)</span> <span class="o">==</span> <span class="s">'json'</span><span class="p">:</span>
<span class="k">return</span> <span class="n">JSONResponseMixin</span><span class="o">.</span><span class="n">render_to_response</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">context</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">return</span> <span class="n">SingleObjectTemplateResponseMixin</span><span class="o">.</span><span class="n">render_to_response</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">context</span><span class="p">)</span>
</pre></div>
</div>
<p>Because of the way that Python resolves method overloading, the local
<tt class="docutils literal"><span class="pre">render_to_response()</span></tt> implementation will override the versions provided by
<tt class="xref py py-class docutils literal"><span class="pre">JSONResponseMixin</span></tt> and
<a class="reference internal" href="../ref/class-based-views.html#django.views.generic.detail.SingleObjectTemplateResponseMixin" title="django.views.generic.detail.SingleObjectTemplateResponseMixin"><tt class="xref py py-class docutils literal"><span class="pre">SingleObjectTemplateResponseMixin</span></tt></a>.</p>
</div>
</div>
<div class="section" id="s-decorating-class-based-views">
<span id="decorating-class-based-views"></span><h2>Decorating class-based views<a class="headerlink" href="#decorating-class-based-views" title="Permalink to this headline">¶</a></h2>
<p>The extension of class-based views isn’t limited to using mixins. You
can use also use decorators.</p>
<div class="section" id="s-decorating-in-urlconf">
<span id="decorating-in-urlconf"></span><h3>Decorating in URLconf<a class="headerlink" href="#decorating-in-urlconf" title="Permalink to this headline">¶</a></h3>
<p>The simplest way of decorating class-based views is to decorate the
result of the <tt class="xref py py-meth docutils literal"><span class="pre">as_view()</span></tt> method.
The easiest place to do this is in the URLconf where you deploy your
view:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">django.contrib.auth.decorators</span> <span class="kn">import</span> <span class="n">login_required</span><span class="p">,</span> <span class="n">permission_required</span>
<span class="kn">from</span> <span class="nn">django.views.generic</span> <span class="kn">import</span> <span class="n">TemplateView</span>
<span class="kn">from</span> <span class="nn">.views</span> <span class="kn">import</span> <span class="n">VoteView</span>
<span class="n">urlpatterns</span> <span class="o">=</span> <span class="n">patterns</span><span class="p">(</span><span class="s">''</span><span class="p">,</span>
<span class="p">(</span><span class="s">r'^about/'</span><span class="p">,</span> <span class="n">login_required</span><span class="p">(</span><span class="n">TemplateView</span><span class="o">.</span><span class="n">as_view</span><span class="p">(</span><span class="n">template_name</span><span class="o">=</span><span class="s">"secret.html"</span><span class="p">))),</span>
<span class="p">(</span><span class="s">r'^vote/'</span><span class="p">,</span> <span class="n">permission_required</span><span class="p">(</span><span class="s">'polls.can_vote'</span><span class="p">)(</span><span class="n">VoteView</span><span class="o">.</span><span class="n">as_view</span><span class="p">())),</span>
<span class="p">)</span>
</pre></div>
</div>
<p>This approach applies the decorator on a per-instance basis. If you
want every instance of a view to be decorated, you need to take a
different approach.</p>
</div>
<div class="section" id="s-decorating-the-class">
<span id="s-id1"></span><span id="decorating-the-class"></span><span id="id1"></span><h3>Decorating the class<a class="headerlink" href="#decorating-the-class" title="Permalink to this headline">¶</a></h3>
<p>To decorate every instance of a class-based view, you need to decorate
the class definition itself. To do this you apply the decorator to the
<a class="reference internal" href="../ref/class-based-views.html#django.views.generic.base.View.dispatch" title="django.views.generic.base.View.dispatch"><tt class="xref py py-meth docutils literal"><span class="pre">dispatch()</span></tt></a> method of the class.</p>
<p>A method on a class isn’t quite the same as a standalone function, so
you can’t just apply a function decorator to the method – you need to
transform it into a method decorator first. The <tt class="docutils literal"><span class="pre">method_decorator</span></tt>
decorator transforms a function decorator into a method decorator so
that it can be used on an instance method. For example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">django.contrib.auth.decorators</span> <span class="kn">import</span> <span class="n">login_required</span>
<span class="kn">from</span> <span class="nn">django.utils.decorators</span> <span class="kn">import</span> <span class="n">method_decorator</span>
<span class="kn">from</span> <span class="nn">django.views.generic</span> <span class="kn">import</span> <span class="n">TemplateView</span>
<span class="k">class</span> <span class="nc">ProtectedView</span><span class="p">(</span><span class="n">TemplateView</span><span class="p">):</span>
<span class="n">template_name</span> <span class="o">=</span> <span class="s">'secret.html'</span>
<span class="nd">@method_decorator</span><span class="p">(</span><span class="n">login_required</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">dispatch</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">):</span>
<span class="k">return</span> <span class="nb">super</span><span class="p">(</span><span class="n">ProtectedView</span><span class="p">,</span> <span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">dispatch</span><span class="p">(</span><span class="o">*</span><span class="n">args</span><span class="p">,</span> <span class="o">**</span><span class="n">kwargs</span><span class="p">)</span>
</pre></div>
</div>
<p>In this example, every instance of <tt class="docutils literal"><span class="pre">ProtectedView</span></tt> will have
login protection.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last"><tt class="docutils literal"><span class="pre">method_decorator</span></tt> passes <tt class="docutils literal"><span class="pre">*args</span></tt> and <tt class="docutils literal"><span class="pre">**kwargs</span></tt>
as parameters to the decorated method on the class. If your method
does not accept a compatible set of parameters it will raise a
<tt class="docutils literal"><span class="pre">TypeError</span></tt> exception.</p>
</div>
</div>
</div>
</div>
</div>
</div>
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<h3><a href="../contents.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">Class-based generic views</a><ul>
<li><a class="reference internal" href="#simple-usage">Simple usage</a></li>
<li><a class="reference internal" href="#generic-views-of-objects">Generic views of objects</a></li>
<li><a class="reference internal" href="#extending-generic-views">Extending generic views</a><ul>
<li><a class="reference internal" href="#making-friendly-template-contexts">Making “friendly” template contexts</a></li>
<li><a class="reference internal" href="#adding-extra-context">Adding extra context</a></li>
<li><a class="reference internal" href="#viewing-subsets-of-objects">Viewing subsets of objects</a></li>
<li><a class="reference internal" href="#dynamic-filtering">Dynamic filtering</a></li>
<li><a class="reference internal" href="#performing-extra-work">Performing extra work</a></li>
<li><a class="reference internal" href="#more-than-just-html">More than just HTML</a></li>
</ul>
</li>
<li><a class="reference internal" href="#decorating-class-based-views">Decorating class-based views</a><ul>
<li><a class="reference internal" href="#decorating-in-urlconf">Decorating in URLconf</a></li>
<li><a class="reference internal" href="#decorating-the-class">Decorating the class</a></li>
</ul>
</li>
</ul>
</li>
</ul>
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